This invention relates to a lubricant-binder additive composition and method for densifying particulate solids and increasing their production rate without increasing the power utilized for densification.
A variety of products manufactured and sold today have a lumpy appearance, but are actually composed of finely divided particulate solids generally formed and compacted under high compressive pressures, and also elevated temperatures, to the desired size and shape. Such processes are broadly referred to as bulk densification. Bulk densification includes the well known processes of pelletization, extrusion, and the like. In these procedures, a primary objective is to obtain a durable, cohesive product which does not break down or disintegrate. A concomitant of these procedures is the relatively large power input required to form the product, often accompanied by a relatively low rate of production.
The products resulting from bulk densification can range in size from small pellets of rat bait and cat liter, usually about one half inch in length in their major dimension, to charcoal briquettes and hay cubes, usually about one to four inches in major dimension, to salt blocks which are usually longer than a foot in length and are used in cattle feeding.
Numerous proposals have been made to improve the bonding between bulk densified particles used in animal feeds, as well as for ways of decreasing power consumption and increasing production rate. Unfortunately, in many situations, an improvement in particle bonding is usually effected at the expense of increased power consumption and reduced production rate, or vice-versa. For example, additives which were found to act as lubricants during the pelleting or extruding steps to reduce power input, often resulted in diminished adhesion between the particles forming the final product.
For example, it is known that the use of vegetable and animal fats, and oils and mineral oils, individually or in combination, result in a substantial decrease in the durability of a bulk densified animal feed product. In order to be effective, that is in order to obtain a lubricating effect sufficient to result in power reduction and/or increased production, these materials generally had to be added in substantial amounts, i.e., from 1% to 2% by weight of the total feed. However, the high concentration of fat or oil additions generally results in a product of low cohesion. Furthermore, high concentrations of fat or oil in the final product are often undesirable for the ultimate product use. For example, high levels of mineral oil, in addition to lowering quality, yield an off color and unpalatable pellet. Tallow is not palatable to ruminants and in many cases excess use results in oily fat animals, such as hogs and chickens, wherein the meat has a greasy and unattractive texture. For this reason dairy feeds and steer feeds cannot use excessive levels of oil and tallow. Additionally, these materials' high viscosity generally makes it difficult to mix with the solid components being densified. Although oils will mix well, tallows are hard at ambient temperatures and require heat to blend into the feed.
Additives have also been utilized to improve the cohesiveness between the particles making up the densified product. These additives are referred to as binding agents. One commonly utilized binding agent for feed products or rat bait, is molasses. Unfortunately, molasses, when used as a binding agent, reduces lubrication and decreases production, resulting in increased power requirements and production costs.
Othe materials, such as clays, more specifically, attapulgite and bentonite, and lignin sulfonate, a byproduct of paper processing, are also effective binding agents, however, provide only a relatively small lubricating effect for the large amount of material to be densified. Generally, such materials must be present in amounts of at least 1% to 2% by weight of the total feed, and thus become a significant proportion of the densified product, but often contribute little in terms of food value of the feed. For example, in terms of a two ton feed batch, this can translate to 20 to 40 pounds of inert material, offering little or no food value.
The densified products described herein, wherein finely divided particles, or grains, are bound directly together by pressure during the pelleting operation must be distinguished from those other products also formed from finely divided particles, but wherein the particles are held within a matrix of a binding agent, such as gelatin, as disclosed for example in U.S. Pat. No. 2,593,577.